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Why I am excited about Clojure

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Re: Why I am excited about Clojure

#121

Post by m0a0t0 »

Totient wrote: post #115

Clojure feels like a 'compromise' Haskell, but I mean that in a good way. Haskell really wants to pretend that everything is a pure function. But I think this is a case where the conceptually simpler thing (i.e. no state) is just too hard to reason about. Clojure backs off the 'referential transparency ONLY' philosophy, and merely discourages mutability. In my (limited) experience, this gives almost all of the advant…

You can still do state using the state monad.

> this gives almost all of the advantages of Haskell

except one of the biggest ones - the type system. Obviously this is subjective though. Some people prefer dynamic typing :)

Re: Why I am excited about Clojure

#122

Post by Morgawr »

DigitalJack wrote: post #95
astine wrote: post #14

That last feature is certainly one of my favorite parts about Clojure. It's one of my favorite parts about Lisps in general actually, but Clojure has a very good handle on it. Having to compile a program before seeing if the changes you made work can be a nuisance. Interpreted programs are slightly better, but being able to make micro-changes to a running instance of a program and seeing in real-time how it affects t…

I admit to still not understanding what goes on with function definitions in clojure, but this idea of just making a micro change in clojure and evaling that and seeing the real time effects never seems to pan out for me. I do lots of small functions that build on each other. If I make a change to one of the base functions, the higher functions seem to hold a reference to the old definition and I end up having to re-…

>And documentation in clojure code in general is very poor. People think their code is self documenting. It is not.

Clojure functions and macros have docstrings you can query with the "doc" function. Honestly I've started keeping a repl open all time like I used to do in C with a terminal + man, so I can use (doc whatever) or (source whatever) to see the documentation + implementation details of most of the functions I use.

Re: Why I am excited about Clojure

#123

Post by patrickmay »

tomp wrote: post #71

> With Clojure your editor (be it Vim, Emacs, Light Table...) is permanently connected to a live REPL. You continually develop, test and modify functions with subsecond feedback. Continuously. Can anyone explain or point me in a direction where I can learn how the above functionality is actually used and useful? I keep hearing about live-editing/hot-reloading, and in theory I believe it must be very useful, but I can…

> What kind of programs can work like that? Continuously running programs, like web servers/GUI programs?

I use Common Lisp and Hunchentoot to build RESTful web applications. I can connect to the Lisp image running on the server using Swank from Emacs on my development box. If there is a bug, I can change the function, recompile it, and test the change with curl, without rebooting the server or reloading the app. The same techniques work for adding new functionality and APIs.

I suggest just giving it a try. It'll change the way you think about building systems.

Re: Why I am excited about Clojure

#124

Post by cies »

lectrick wrote: post #32

I am a Ruby guy torn between diving into Haskell or Clojure. Help! Every time I get excited about one feature of one (ClojureScript) I learn the other has something equivalent or potentially better (Haste). One thing that has put me off on Clojure is 1) the ugly as hell JVM stacktraces, 2) hitting the wall of the number system results in nasty JVM errors if you are used to Ruby's trivial (to the developer at least) h…

I went for Haskell. I think Clojure is too close to Ruby in the respect that there is not much safety build in. And I --like you-- am JVM-averse. :)

Re: Why I am excited about Clojure

#125

Post by Periodic »

chongli wrote: post #69
seacious wrote: post #44

Earlier quoted context omitted.

Not having to memorize an operator precedence table makes me more than willing to give up syntactic sugar. This is one of the things that I dislike most about haskell. I wish liskell or one of the other projects trying to bring S-expressions to haskell had taken off.

There's nothing stopping you from using more parens in your own Haskell code; I definitely use them.

I find if I'm using parentheses to group (non-numeric) expressions in Haskell then I should probably break up the expression and name the parts.

One wonderful thing about Haskell is that there isn't a cost to using let expressions, even if some of the values will never be used. Laziness means I can freely decompose my complex expressions into clearly named components and not worry about doing unnecessary computation.

Re: Why I am excited about Clojure

#126

Post by stcredzero »

astine wrote: post #28
Zak wrote: post #25

Earlier quoted context omitted.

What I find really surprising is that other languages that have pretty decent REPL support have not embraced it so fully as Lisps have. Connecting to the live[0] instance a Rails or Django app, examining its internal state and making updates that don't involve more or less restarting the app is unusual at best. Ruby and Python borrow a lot from Lisp, including the REPL, but some of the most popular applications of th…

I'll stipulate that you might want to be very conservative about doing this with a production system. No kidding. I knew at least one guy who hosed a product launch by doing that. You even have to restart your development instance from time to time to make sure that your application state remains consistent. I've been scared to try, but I suspect that you could live-patch a server though if you were systematic about…

Back in 2001, We had a corner case bug in our ORM that impacted a scheduled demo. So I connected with the live Smalltalk app server and changed the state of the DB locks during the demo.

There are technologies deigned to enable live updates. VisualWorks Smalltalk had one, though it was not widely used. There are real time OS that can update the kernel without going down.

Re: Why I am excited about Clojure

#127

Post by th0ma5 »

yogsototh wrote: post #118
erichmond wrote: post #64

Earlier quoted context omitted.

I'm curious how Haskell could be a clear winner for production code, particularly as it pertains to efficiency and time. Clojure sits on top of the JVM, and as such, has the benefit of interop with some of the most robust software packages in the world. Unless I'm missing something, you'd need to roll your own packages in Haskell for all this functionality. I would argue that the most efficient code is well maintaine…

One of little secret of Clojure is that you almost never use Java based library. Because it forces you not to use idiomatic Clojure. So, most library you'll use in Clojure are in fact Clojure made. From this point of view of number of libraries, Haskell and Clojure are in fact at the same level. I was sold in part by the JVM argument. But in reality, in practice, I found it to be more a burden than a delight. First,…

Just a minor point, some of the build tools allow you to make a .war file, and that you can just copy into Tomcat if you want.

Re: Why I am excited about Clojure

#128

Post by visarga »

platz wrote: post #84
guiomie wrote: post #55

I'm a C# guy at work, I also do some front-end in javascript (with angularjs sometimes). For side-projects I like to use node.js. I want to learn another language, and I've been wondering wether I should go with Clojure or C++ ? My dilenma is "Do I want to learn more about programming style running on VMs (functional) or do I want to dive into barebone high performance code ?" I've done C and Java at university, but…

I'm a C# guy at work too. I can't say I've touched much C++ outside of college also a while ago, but I've been studying functional programming for a while and really enjoying the new concepts it teaches. It can be a bit humbling at times though. I got some good perspective with https://www.coursera.org/course/proglang and you could do worse than taking grossman's excellent course. It helps to have some structure and…

For some reason the Programming Languages class is offline now.

Re: Why I am excited about Clojure

#129

Post by wink »

mduerksen wrote: post #114
wtetzner wrote: post #65

Earlier quoted context omitted.

One thing I've noticed is that the JVM startup time is actually pretty small. What's slow is waiting for Clojure to bootstrap itself.

JVM Feature Request: The ability to preserve a complete JVM state (in this case with loaded Clojure stuff) and quickly start from there. Does anybody know if something like that is possible/already exists?

https://github.com/ninjudd/drip

http://www.martiansoftware.com/nailgun/

http://leiningen.org/grench.html

All 3 not perfect, but have a look :)

Re: Why I am excited about Clojure

#130

Post by aaron-lebo »

yogsototh wrote: post #118
erichmond wrote: post #64

Earlier quoted context omitted.

I'm curious how Haskell could be a clear winner for production code, particularly as it pertains to efficiency and time. Clojure sits on top of the JVM, and as such, has the benefit of interop with some of the most robust software packages in the world. Unless I'm missing something, you'd need to roll your own packages in Haskell for all this functionality. I would argue that the most efficient code is well maintaine…

One of little secret of Clojure is that you almost never use Java based library. Because it forces you not to use idiomatic Clojure. So, most library you'll use in Clojure are in fact Clojure made. From this point of view of number of libraries, Haskell and Clojure are in fact at the same level. I was sold in part by the JVM argument. But in reality, in practice, I found it to be more a burden than a delight. First,…

> One of little secret of Clojure is that you almost never use Java based library. Because it forces you not to use idiomatic Clojure. So, most library you'll use in Clojure are in fact Clojure made. From this point of view of number of libraries, Haskell and Clojure are in fact at the same level.

This isn't really true.

Yes, directly using a Java library forces you to use Clojure that is not idiomatic but 1) this isn't always the case 2) there are idiomatic wrappers over some libraries already.

More importantly, at least you have the option of using Java libraries. Having to use Clojure code that is not idiomatic still will be much more productive than writing the library yourself in Haskell.

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